The recent earthquakes in Japan and Ecuador happened within hours of each other, killing several hundred people. While both quakes were equally devastating for the countries and people involved, neither disaster has reached the scale experienced by Nepal last year.
Between 1900 and 2015, there have been over 2.5m fatalities globally due to earthquakes, 30% of these have occurred since 2000.
The period 2000-2009 was the worst decade for earthquake fatalities on record, with more than half a million people killed. The current decade (2010-2019) is already on track to exceed that, with more than 350,000 people killed in earthquakes to date.
Of the five most deadly earthquakes in documented history, two have occurred since 2000; the 2004 Indian Ocean earthquake that killed more than a quarter of a million people and the catastrophic 2010 Haiti earthquake – which has the highest death toll for an earthquake ever officially recorded (316,000). The 2000s also saw earthquakes in China, Pakistan, Iran and Japan take a combined total of more than 200,000 lives.
While the scale of these numbers is often shocking and highly emotive, it’s important that debates on the underlying science and appropriate mitigation are undertaken with care.
Global population growth and urbanisation, especially in Asia, is certainly one factor influencing the high death toll. Asia currently has the highest number of mega-cities in the world, most of which are growing fast, with some expected to grow by more than 46% by 2030.
The number of people living in earthquake zones is now greater than ever before. This includes those living on the Pacific Ring of Fire – a long chain of volcanoes and other active structures surrounding the Pacific Ocean – and along the Alpine-Himalayan belt. This means earthquakes that would previously have killed hundreds now kill thousands or tens of thousands as a result of increased exposure.
But increased exposure is by no means the only factor. The adage that earthquakes don’t kill people buildings do, highlights a key challenge in increasing resilience to earthquakes.
The scale of the problem is apparent when we consider that a 2007 study estimated that 90% of buildings in Iran and Nepal – two countries known to have high earthquake risk – had limited earthquake safety. But this problem isn’t unique to Asia. The same study estimated 60-80% of buildings in Austria, which is notably earthquake prone, were similarly vulnerable as a result of low earthquake awareness among professionals.
Reducing the risk
While the knowledge needed to construct earthquake safe buildings is available – even in some of the world’s poorest nations – its implementation remains challenging. A combination of weak governance, limited capacity and resources leaves this task seemingly insurmountable.
This is further exacerbated because earthquake disasters in any one location are actually quite rare – before 2015, the previous major earthquake in Nepal was 81 years ago – and so memories of just how catastrophic earthquakes can be quickly fade.
Our research is taking a new approach by using “scenarios” based on observations from previous events to simulate the hazards that result from an earthquake. These are then implemented using civilian or military simulations that help to test the abilities of first-responders during a disaster.
Scenarios are designed to simulate the consequences of an earthquake without having to experience one firsthand. They help to demonstrate the potential scale of earthquake impacts but also quantify how proposed mitigation – such as enforcing earthquake safe building codes – can have major positive effects.
By simulating changes to the current building stock, we can estimate how many lives could be saved as a result of efforts to increase resilience to earthquakes, for example. We know that buildings made from mud brick and earth are particularly vulnerable to earthquakes and replacing these could lead to substantial reductions in earthquake fatalities.
While our findings could aid decision makers, one criticism of this scenario approach is the focus upon a single event – which is by definition not the event that will happen next. However, we can explore multiple scenarios and assess where repeated losses recur – irrespective of the precise nature of each scenario tested. Major losses in different scenarios can then be identified and prioritised for mitigation. This approach allows us to consider how to address future earthquake losses, but it’s by no means a perfect solution.
In all earthquake prone nations seismic risks are just one of the many areas in need of investment. Consequently, it is often the nations with weak governance and the most limited resources that see the biggest loss to life from earthquakes. In these countries efforts to reduce such risks are superseded by the need to address livelihood demands such as clean water.
For countries like Nepal, where seismic risk is considered to be particularly pervasive, this approach can help ensure earthquake risk is considered and prioritise where to deploy the limited resources that are available.
As well as this, we need to continue to explore new ways to make buildings more resilient to earthquakes, but this needs to be coupled with methods to make these efforts sustainable, cost effective, and prioritised by decision makers.
So while we can’t eliminate earthquake fatalities entirely, we can certainly work harder and smarter to reduce the losses and devastation that seem to go hand in hand when an earthquake hits.